Learn Swift on the Mac: For OS X and iOS

Chapter    8

Functions and Closures

Functions are self-contained blocks of code that perform a specific task. Swift’s functions are very flexible. They can be very simple, such as the println or print functions, or very complex.

• They can be simple C-style functions with no parameter names.
• They can have local and external parameter names for paramters, similar to Objective-C.
• They can have parameters that provide default values.
• They can return multiple values.
• They can be passed as arguments.
• They can be returned as a result from other functions.
• They can have nested functions.

Defining Functions

The general format for a function starts with the keyword func, followed by the name of the function, optional arguments, and an optional return ...